To determine which animal shelter has the dog that weighs the least, we can look at the whisker ranges of both shelters:
- For Shelter A, the whiskers range from 8 to 30, indicating that the lightest dog weighs 8 pounds.
- For Shelter B, the whiskers range from 10 to 28, indicating that the lightest dog weighs 10 pounds.
Thus, the dog that weighs the least is in Shelter A, which has a dog that weighs 8 pounds.
Therefore, the correct answer is: shelter A.